This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A037456 #9 Aug 03 2014 14:27:16
%S A037456 0,1,2,8,9,10,16,17,18,64,65,66,72,73,74,80,81,82,128,129,130,136,137,
%T A037456 138,144,145,146,512,513,514,520,521,522,528,529,530,576,577,578,584,
%U A037456 585,586,592,593,594,640,641,642,648,649,650,656,657,658,1024
%N A037456 a(n)=Sum{d(i)*8^i: i=0,1,...,m}, where Sum{d(i)*3^i: i=0,1,...,m} is the base 3 representation of n.
%H A037456 Clark Kimberling, <a href="/A037456/b037456.txt">Table of n, a(n) for n = 0..1000</a>
%t A037456 Table[FromDigits[RealDigits[n, 3], 8], {n, 1, 100}]
%t A037456 (* _Clark Kimberling_, Aug 14 2012 *)
%K A037456 nonn,base
%O A037456 0,3
%A A037456 _Clark Kimberling_
%E A037456 offset changed to 0.